Bolus of saline

My mother was given a total of 2.5 to 3 liters of boluses of saline due to low BP after hip replacement .her BP was 70 systolic later on went up 110 systolic after 1 hour on bolus She is a petite lady only 78 lbs 4'7 in height and have renal insufficiency after repeated boluses her stomach got bigger and later on her R thigh got big (edema) next morning she complained of chest pain and pass away I don't what the cause of her sudden death is there any negligent care involve here pls advise.